Well known are yarn treating technologies wherein a yarn is subjected to a fluid jet, in general an air jet. The technologies are classified into three types: a first technology wherein filaments constituting a yarn are interlaced with each other so that the yarn is provided with a high coherency; a second technology wherein loops or false-twists are imparted into filaments constituting a yarn so that the yarn is provided with a high volume; and a third technology wherein twist torque is imparted to a yarn so that the yarn is provided with high twists.
The present invention relates to an apparatus which is utilized for yarn treatment belonging to the above-mentioned first technology which hereinbelow will be referred to as "interlacing".
Many apparatus for interlacing are disclosed in prior arts, for example United States Pat. No. 2,985,995, British Pat. No. 1,301,500 and Japanese Patent Publication No. 18056/72.
The inventors of the present invention conducted a careful investigation regarding behaviors of a yarn and filaments constituting the yarn during the interlacing operation. As a result, they found, that in order to obtain an interlaced yarn which is uniformly interlaced at a high level, the unidirectional and continuous rotation of the yarn during the interlacing operation is required to be maintained as minimal as possible and that the yarn is required to be subjected to a stable, periodical and sufficient opening operation.
Based on the result, they then conducted research for actual design of an interlacing apparatus which can satisfy the requirements. As a result, to minimize the unidirectional and continuous rotational movement of a yarn, it is confirmed that the shape of a peripheral wall of an interlacing chamber, which wall extends along the yarn passage, must be so selected that the unidirectional and continuous rotational movement of the yarn does not occur. It is also confirmed that the location and direction of a fluid jet nozzle must be so selected that the yarn does not produce a unidirectional and continuous rotation when it is subjected to a movement of the fluid jet after the fluid jet ejected from the fluid jet nozzle has impinged upon the yarn. Similarly, to impart a periodic and sufficient opening operation to the yarn, it is confirmed that a surface to which the yarn is periodically pressed, so as to be open fully, must be formed on a part of the peripheral wall of the interlacing chamber. Furthermore, it is confirmed that, to decrease the unidirectional and continuous rotational movement of the yarn in the interlacing chamber and to maintain the periodical and sufficient opening operation of the yarn, it is preferable that the peripheral wall of the interlacing chamber which extends along the axis of the chamber is enclosed. When a string-up slit for introducing a yarn to the interlacing chamber upon the commencement of the yarn treatment or for discharging the yarn from the interlacing chamber upon the stoppage of the yarn treatment is formed on the interlacing chamber, the string-up slit must be formed at a carefully selected position so that stability is maintained.